Insulator



Patented Oct. 8, 1940 PATENT OFFICE IN SULATOR Thomas H. Morcom, Rochester, N. Y., assignor to General Railway Signal Company, Rochester,

Application July 26, 1938, Serial No. 221,381

3 Claims.

This invention relates in general to insulators, and has more particular reference to a molded type of insulator for use in connection with relays and the like.

In the manufacture of relays for railway use particularly, it is desirable to securely fasten the contact lingers to the armature by insulating meansy which can stand a relatively high voltage without breakdown and which are mechanically l() strong, and still are small and compact in size whereby to economize in space.

With the above and other objects in View, it is proposed, in accordance with this invention, to provide a relatively' small, compact, molded insulator for connecting contact fingers to relay armatures and fork other similar uses which will have high insulating qualities and great physical strength in proportion to their size.

Further objects, purposes and characteristic features will appear as the description progresses,

reference being made to the accompanying drawing, showing, in a wholly diagrammatic manner, and in no means in a limiting sense, one form which the invention can assume. In the drawine- Fig. l is a fragmentary elevational View of insulators, in accordance with this invention, as employed in a relay.

Fig. 2 is a longitudinal sectional view, to an enlarged scale, of an insulator in accordance with this invention.

Fig. 3 is an end view of one of the threaded studs constituting part of the insulator.

Fig. 4 is a side View .of the stud of Fig. 3.

Fig. 5 is an end View of the other stud constituting part of the insulator.

Fig. 6- is a side view of the stud of Fig. 5.

Referring now to the drawing, and first to Fig. 1, there is here shown a portion of a relay including a pole shoe I, for operating an armature 2, which is pivoted at 3, to a stationary portion 4 of the relay. Carried by armature 2 is a contact nger 5, connected to the armature by means oi two studs, each designated generally as S.

Each stud S, as best seen in Fig, 2, is comprised of a body 6, of molded insulating material, in the form of a short cylinder, with projecting threaded stems I and 8, oi the stwo studs, the heads of which are embedded in the insulating material. The threaded stem 'I is screwed into the armature Z, While the threaded stem 8 passes through the finger 5 and is clamped thereto by a nut, or the like, 9.

Referring now more particularly to Fig. 2,

wherein an insulator is shown in longitudinal section, it can be seen that the molded insulating material constituting the body 6, has embedded therein the heads of the two studs having threaded stems 'I and 8.

The head BH carried by stem 8, is in the `5 form of a cup or bell, and the head and stud can be conveniently referred to as the bell head and the bell stud; while the stem 'I carries a head Sl-l, in the form of a spigot, and the head and stud can oe conveniently termed the spigot head 10 and the spigot stud.

The bell head BH, is constituted by a base 0r bottom member I0, with a forwardly projecting rim or annular side member II, forming the socket of the bell, with screw threads I2 formed 15 on the inner face of the annular side iI, these threads extending to where the bottom inner surface i3 of the base connects with the side II. On the outer cylindrical face I4 of the bell, is formed a plurality of grooves I5 of semi-circular 20 cross section and encircling the side II. Also formed in the side Il, are two relatively deep transverse slots i6, which can be milled or otherwise formed in the side member, and are preferably arranged diametrically opposite each 25 other.

In the case of the spigot stud, the head is constituted by a relatively thick disc-like portion I'I, with a centrally forwardly projecting iinger i8. On the outer cylindrical face of disc I'I is formed 30 one or more grooves 69, similar to the grooves I5 in the bell stud. Across the inner ilat face of disc I'I, are formed two parallel spaced slots 2B, which may be milled or sawed, and which are spaced so as to each cut oli a portion of the cy- 35 lindrical face of linger I8, so as to form two parallel fiat diametrically opposed faces 2| and 22 on nger I8. The finger I8 is also supplied with a plurality of grooves 23 semi-circular in cross section, spaced along its length, and of a char- 40 acter similar to the grooves I5 and I9, described above.

The two studs SH and BH have their stems I and 8 positioned in line with each other, and along the axisI of cylinder 6, and are molded into 45 the cylinder 6 in a position where linger I8 projects a considerable distance into the bell of the other stud.

The studs are made of brass, or other suitable material, while the insulating material con- 50 stituting member 6 can be Bakelite, or similar material, which can be readily molded to shape.

With the construction described above, it is clear that the bell stud is prevented from being withdrawn axially from the insulating material by 55 the grooves I5, and also by the threads i2. Also this member is prevented from being turned in the insulating material by means of the diametrically opposed slots I6.

In the case of the spigot stud, the stud is prevented from being axially withdrawn from the insulating material by the grooves I9, and the grooves 23, and is prevented from being turned in the insulating material by the two parallel grooves 20, and the flat sides 2l and 22 on finger IS.

It should be noted that the two studs have their heads separated at every point by insulating material, and are so icrrned and positioned that the thinnest amount oi insulating material between the two heads at various points is substantially the same. rihis insulation is suiiicient, in the case of a stud of this construction, and of a size onen quarter or" that shown in Figs. 34S, to withstand an alternating current voltage of 7560 volts without breakdown, and to stand a tensile strain of 180 pounds along the axis of the threaded stems l' and 3.

By arranging the heads of the studs as described above, and as shown best in Fig. 2, so that the projecting part i8 of one head is received within the socket of the other head, the heads of the studs can be relatively long and still the entire insulator can be relatively short. In other words, each of the stud heads is considerably more than hair oi the length oi the insulating cylinder 6, and still sufficient insulating material is retained between the heads of the studs, even at the thinnest parts, to provide a high insulating value.

In Fig. 2, the insulating material within the slots i6, of stud BH, has been removed, in order to better show the structure involved.

The heads of the two studs are allowed to project beyond the ends of the cylinder of molded insulating material, a slight extent, in order to bear against the parts interconnected by the studs, and thus prevent crushing of the insulating material.

The above rather specific description of one form which this invention can assume, has been given solely by way of example, and is not intended., in any manner whatsoever, in a limiting sense. It is to be understood that all such modifications and variations, which may occur in practice, and which fall within the scope of the appended claims, are intended to be covered by the present application.

Having described my invention, I now claim:

l. In an insulator, in combination, a cylinder of molded insulating material, a threaded stud in each end of the cylinder each with its threaded stem projecting outwardly from the cylinder and its head embedded in the cylinder, the head of one stud being a bell head which is cylindrical externally, hollow and bell shaped internally, the head of the other stud being a spigot head and generally disc shaped with a centrally positioned iinger projecting therefrom and into the opening of the bell of the bell head to substantially half of the depth oi the hollow part of the bell, screw threads on the inner face of the bell of the bell head, diametrically opposed radial slots in the edge of the bell, a groove encircling the cylindrical face of the disc of the spigot head, and parallel spaced slots in, and completely crossing, the inner face of the disc.

2. In an insulator, in combination, a cylinder of molded insulating material, a threaded stud in each end of the cylinder each with its threaded stem projecting outwardly from the cylinder and its head embedded in the cylinder, the head of one stud being a bell head which is cylindrical externally, hollow and bell shaped internally, the head of the other stud being a spigot head and generally disc shaped with a centrally positioned finger projecting therefrom and into the opening oi the bell of the bell head to substantially half of the depth of the hollow part of the bell, screw threads on the inner face of the bell of the bell head, diametrically opposed radial slots in the edge of the bell, a groove encircling the cylindrical face of the disc oi the spigot head, parallel spaced slots in, and completely crossing, the inner face oi the disc, the outer cylindrical face of the bell head carrying a plurality of parallel grooves, of semi-circular cross section, completely encircling the head, and a plurality of parallel grooves in the finger of the spigot head and at right angles to the longitudinal axis of the finger.

3. In an insulator, in combination, a cylinder of molded insulating material, a threaded stud in each end of the cylinder each with its threaded stem projecting outwardly from the cylinder and its head embedded in the cylinder, the head of one stud being a bell head which is cylindrical externally, hollow and bell shaped internally, the head of the other stud being a spigot head and generally disc shaped with a centrally positioned finger projecting therefrom and into the opening of the bell oi the bell head to substantially half of the depth of the hollow part of the bell, screw threads on the inner face of the bell of the bell head, diametrically opposed radial slots in the edge of the bell, a groove encircling the cylindrical face of the disc of the spigot head, parallel spaced slots in, and completely crossing, the inner face of the disc, the outer cylindrical face of the bell head carrying a plurality of parallel grooves completely encircling the head, and a plurality of parallel grooves in the iinger of the spigot head and at right angles to the longitudinal axis of the finge-r, the parallel spaced slots in the disc of `the spigot head extending inwardly toward the axis of the finger far enough to include diametrically opposed longitudinal portions of the finger.

THOMAS H. MORCOM, 

